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https://issues.apache.org/jira/browse/HBASE-8370?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13694320#comment-13694320
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Elliott Clark commented on HBASE-8370:
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We don't have per block type metrics in trunk/95 because the overall cache hit
percentage is a good proxy for data block cache percent. Yes the overall
number is higher but it still gives a good actionable number. You can know if
you're doing better or worse than you were before. Even better is the
derivative of cache miss count.
Overall SchemaMetrics cost HBase about 10% of it's performance and I just don't
think the enough people got enough out of it to keep per cf per block type
metrics.
Maybe we should show the percentage to more decimal figures so that it's more
obvious that there are some misses? But overall while the UI is nice it's not
what should be used for figuring these things out. That should be done by your
metrics system (CM, Ganglia, OpenTSDB, etc).
> Report data block cache hit rates apart from aggregate cache hit rates
> ----------------------------------------------------------------------
>
> Key: HBASE-8370
> URL: https://issues.apache.org/jira/browse/HBASE-8370
> Project: HBase
> Issue Type: Improvement
> Components: metrics
> Reporter: Varun Sharma
> Assignee: Varun Sharma
> Priority: Minor
>
> Attaching from mail to d...@hbase.apache.org
> I am wondering whether the HBase cachingHitRatio metrics that the region
> server UI shows, can get me a break down by data blocks. I always see this
> number to be very high and that could be exagerated by the fact that each
> lookup hits the index blocks and bloom filter blocks in the block cache
> before retrieving the data block. This could be artificially bloating up the
> cache hit ratio.
> Assuming the above is correct, do we already have a cache hit ratio for data
> blocks alone which is more obscure ? If not, my sense is that it would be
> pretty valuable to add one.
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